Answer:
he predicted the properties from known elements above and belws the unknown in the same group
Explanation:
What allowed Mendeleev to make predictions of undiscovered elements
He realized that an element on this table with one known element above it and one known element below it had to have properties between the two known elements
How did Mendeleev predict gallium and germanium?
Based on gaps in the periodic table Mendeleev deduced that in these gaps belonged elements yet to be discovered. Based on other elements below and above in the same group he predicted the existence of eka-aluminum, eka-boron, and eka-silicon, later to be named gallium (Ga), scandium (Sc), and germanium (Ge).
First, calculate the mass of sodium in g with the help of molar mass and number of moles.
Number of moles = 
(1)
Molar mass of sodium =
Substitute the given value of number of moles and molar mass of sodium in formula (1)
(1)
(1)
mass of sodium in g = 
Now, according to conversion factor, 1 g = 1000 mg
So, of sodium = 
= 
of sodium
Thus, mass of sodium in mg =
Answer:
Avogadro's number is 6.022×1023 molecules. With Avogadro's number, scientists can discuss and compare very large numbers, which is useful because substances in everyday quantities contain very large numbers of atoms and molecules.
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Answer:
A feasible error could have been the removal of the sample before all water evaporated.
Explanation:
In order to determine the percentage of water in an hydrate, an experiment that could be performed is the heating of the sample until the mass does not change. If the student heated the sample an insufficient amount of time, water will be present in the sample, thus reducing the percentage reported.
